Open-end spinning device

ABSTRACT

The invention concerns an open-end spinning device with two friction rollers driven in the same direction and forming a spinning nip of which the roller rotating towards the spinning nip is a suction roller and in which the fibers fed into the spinning nip are twisted together into a thread in a yarn forming zone. At least one of the friction rollers (1, 2) is provided with a sector (I) subjected to negative air pressure in the spinning nip, in the range of the yarn forming zone (G). The width of said sector (I) extends, in the peripheral sense, from the yarn forming zone (G) to beyond the plane (A) connecting the axes of the friction rollers (1, 2) towards the side opposite to the spinning nip (3).

BACKGROUND AND SUMMARY OF THE INVENTION

The invention concerns an open-end spinning device with two frictionrollers driven in the same direction and forming a spinning nip, ofwhich the friction roller rotating towards the spinning nip is a suctionroller, whereby the fibers fed into the spinning nip are twistedtogether into a thread in a yarn-forming zone.

In such a spinning device the friction rollers are provided with sectorssubjected to negative air pressure so that the fibers are caused to flyinto the nip area (DE-PS-No. 24,49,583). It also suffices if only one ofthe friction rollers is subjected to negative air pressure (EP-OS No.00,62,404). In order to facilitate the flight of the fibers thesesectors are large, in relation to the friction rollers' periphery, andare located on the side of the spinning nip, in the peripheral sense.Because of the size of the suction sectors air consumption is high inthese devices. It has furthermore been shown that in such spinningdevices the quality of the yarn deteriorates considerably at highspinning speeds.

It is the objective of the present invention to avoid the disadvantagesand to create a device making it possible to spin a yarn of goodquality, even at high spinning speeds.

This objective is attained in a device according to the introductoryclause of claim 1 of the invention by providing at least one sectorsubjected to negative air pressure in the range of the yarn formingzone, in the spinning nip, whereby the width of said sector extends, inthe peripheral sense, from the yarn forming zone to beyond the planeconnecting the axes of the friction rollers towards the side opposite tothe spinning nip. It was also shown that such as arrangement or thesuction zone has a very beneficial influence upon the imparting ortorsion to the yarn.

The sector subjected to negative air pressure can be very narrow, with awidth from 4 to 8 mm and preferrably 6 mm wide, so that air consumptionis extremely low. The middle of the sector subjected to negative airpressure is located within the plane connecting the axes above thefriction rollers or at a distance of the axes-connecting plane, in theperipheral sense, on the side opposite to the spinning nip. Thus asuction zone of sufficient size for the required air flow rate isobtained, yet a concentration upon the yarn forming zone is achieved. Ithas been shown that the imparting of torsion to the yarn is greatlyenhanced with such a design, even at high spinning speeds. Conveying ofthe fibers is enhanced if a sector of lesser negative air pressureprocedes the sector of great negative air pressure on the frictionroller rotating towards the spinning nip. Best results from the point ofview of yarn strength are obtained if the middle of the sector subjectedto suction air is spaced extends 1 mm from the plane connecting thefriction rollers, on the side opposite to the spinning nip.

BRIEF DESCRIPTION OF THE DRAWINGS

An example of the invention is described below through the followingdrawings.

FIG. 1 shows a spinning device according to invention in cross-section.

FIG. 2 shows the spinning nip area with a sector of greater negative airpressure.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows two friction rollers 1 and 2 located parallel to and inclose proximity of each other. The friction rollers 1 and 2 form aspinning nip 3 in which the fed fibers are twisted into a yarn. Toachieve this the frictions rollers 1 and 2 are driven in the samedirection in a manner not shown here in further detail.

The friction roller 1, rotating towards the spinning nip 3, is equippedwith a perforated casing surface 10 and with a connected suction insert11. The suction insert 11 is provided with a slit 12 in the area of thespinning nip 3, extending in the longitudinal sense of the spinning nip3, whereby the suction air stream is produced through said slit. Thefriction roller 2, rotating away from the spinning nip 3, is notperforated and is not subjected to suction air. The negative pressurezone of the friction roller 1 rotating towards the spinning nip 3extends from a limit wall 15 up to the spinning nip 3 and ends there ata limit wall 14. The limit wall 15 is located before a collecting groove4, in the rotational sense of the friction roller 1, to be described ingreater detail hereinbelow.

The negative pressure zone of the friction roller 1 is subdivided by aseparating wall 13 into two sectors I and II of different suctioneffect, whereby the sector I, forming the slit 12, is preferrablysubjected to greater negative air pressure in the yarn forming zone. Thenegative air pressure in sector II merely ensures that the fibers areheld securely on the friction roller 1 as they are conveyed into thespinning nip 3 and is kept suitably low. On the other hand, the negativepressure in sector I must be sufficiently great so that proper spinningis ensured. It has been found here that with an appropriately calculatednegative air pressure in the yarn forming zone G it is possible toobtain especially good spinning results from the point of view of yarnstrength if the sector I, forming the slit 12, is from 4 to 8 mm wide,in the peripheral sense, and preferrably 6 mm wide, and if it is spacedapproximately 1 mm from the axes-connecting plane A of friction rollers1 and 2 on the side opposite to the spining nip 3. Insofar as thefriction roller 2 is also a suction roller, this also applies for theslit of said friction roller 2, across from sector I. In tests increasedyarn strength was also obtained if, as FIG. 2 shows, the middle ofsector I was located in the plane A connecting the friction rollers 1and 2 or was located at approximately 1 mm from the axes-connectingplane A in the direction of the side opposite to spinning nip 3. This isindicated by the broken line in FIG. 2.

The collecting groove 4, mentioned earlier, in front of which thenegative air pressure zone of sector II begins, is formed by the casingsurface 10 of the friction roller 1, rotating towards the spinning nip,and by a moving guiding surface 50. This guiding surface 50 is thesurface of an endles band 5 and reaches into the spinning nip 3. Theendless band 5 is guided over deflection rollers 51, 52 and 53 and ispressed by at least one clamping roller 54 against the casing surface 10of the friction roller 1, so that the guiding surface 50 is in contactwith the friction roller 1 at the bottom of the collecting groove 4. Thecontact pressure of clamping roller 54 is increased by a spring, so thatthe band 5 is securely driven by friction roller 1, whereby theperipheral speed of the guiding surface 50 in the collecting groove 4 issynchronized with the pheripheral speed of friction roller 1.

The fiber material to be spun is fed in the conventional manner, in formof a fiber sliver, to an unravelling device (not shown) which separatesit into single fibers. The single fibers are fed through a fiber channel(not shown), preferrably in the longitudinal sense of collecting groove4 into said groove where they are collected and brought together into afiber formation. The fiber formation, held fast by the suction airstream on the casing surface 10 of the friction roller 1 is givengreater cohesion and forced guidance to the spinning nip 3 as it leavesthe collecting groove 4 through the moving guiding surface 50, incontact with the casing surface 10. In this manner, a predoubled, evenfiber formation arrives in the spinning nip 3 and the quality of theyarn is thereby improved.

I claim:
 1. An open-end spinning device for spinning fibers, comprisingtwo friction rollers driven in the same direction and forming a yarnforming zone and a spinning nip therebetween for receiving fiberswherein the friction roller rotating towards the spinning nip in thedirection which the spinning nip receives fibers is a suction roller,whereby the fibers received by the spinning nip are twisted togetherinto a yarn in a yarn forming zone, wherein at least one of the frictionrollers is provided with a first sector subjected to negative airpressure in the spinning nip, in the range of the yarn forming zone,whereby the width of said first sector extends, in the peripheral sense,from the yarn forming zone to beyond a plane connecting the axes of thefriction rollers towards the side opposite to the spinning nip, andfurther comprising a second sector of lesser negative pressure than saidfirst sector on the suction roller preceding said first sector forconveying fibers into the yarn forming zone.
 2. An open-end spinningdevice as defined in claim 1, wherein the width of the first sectormeasures from 4 to 8 mm.
 3. An open-end spinning device as defined inclaim 1, wherein the width of the first sector measures 6 mm.
 4. Anopen-end spinning device as defined in claim 1 or 2, wherein thefriction roller rotating towards the spinning nip is provided with thefirst sector and the first sector is provided with suction, while thefriction roller rotating away from the spinning nip is not subjected tosuction.
 5. An open-end spinning device as defined in claim 1 or 2,wherein the middle of the first sector is located at a distance from theplane connecting the axes of the friction rollers in the peripheralsense, on the side opposite to the spinning nip.
 6. An open-end spinningdevice as defined in claim 4, wherein the middle of the first sector islocated at a distance from the plane connecting the axes of the frictionrollers in the peripheral sense, on the side opposite to the spinningnip.
 7. An open-end spinning device as defined in claim 1 or 2, whereinthe first sector extends by approximately 1 mm, on the side opposite tothe spinning nip, beyond the plane connecting the axes of the frictionrollers.
 8. An open-end spinning device as defined in claim 1, furthercomprising: a casing surface through which suction may be applied; amoving guide surface for moving fibers towards the spinning nip; and acollecting groove spaced from said spinning nip, said collecting groovebeing defined by said casing surface rotating in a direction fordelivering fibers to the spinning nip and by said moving guide surface;said moving guide surface moving in said direction for delivering fibersto the spinning nip at a speed substantially equal to the surface speedof said casing surface.
 9. An open-end spinning device for spinningfibers together into a thread, the open-end spinning devicecomprising:two friction rollers for being driven in the same direction,said two friction rollers defining a spinning nip and a yarn formingzone therebetween for receiving and twisting the fibers into thread; atleast one of said two friction rollers rotating in a direction fordelivering the fibers to said spinning nip, said at least one of saidtwo friction rollers having a casing surface through which suction maybe applied; said at least one of said two friction rollers being forconveying the fibers received thereby on said casing surface thereofinto said spinning nip; a first suction section association with said atleast one of said two friction rollers for providing suction in saidspinning nip in the range of said yarn forming zone, said first suctionsector extending peripherally about said casing surface from said yarnforming zone to said spinning nip; and a second suction sector of lessersuction than said first suction sector associated with said at least oneof said two friction rollers for providing suction about said casingsurface, said second suction sector preceding said first suction sectorfor conveying fibers into the yarn forming zone.
 10. An open-endspinning device for spinning fibers together into a thread, the open-endspinning device comprising:two friction rollers for being driven in thesame direction, said two friction rollers defining a spinning nip and ayarn forming zone therebetween for receiving and twisting the fibersinto threads; at least one of said two friction rollers rotating in adirection for delivering the fibers to said spinning nip, said at leastone of said two friction rollers having a casing surface through whichsuction may be applied, said at least one of said two friction rollersbeing for conveying the fibers received thereby on said casing surfacethereof into said spinning nip; a first suction sector associated withsaid at least one of said two friction rollers for providing suction insaid spinning nip in the range of said yarn forming zone, said firstsuction sector extending peripherally about said casing surface fromsaid yarn forming zone to said spinning nip; a second suction sector oflesser suction than said first suction sector associated with said atleast one of said two friction rollers for providing suction about saidcasing surface, said second suction sector preceding said first suctionsensor for conveying fibers into the yarn forming zone; a moving guidesurface for moving fibers towards said spinning nip; and a collectinggroove spaced from said spinning nip, said collecting groove beingdefined by said casing surface rotating in said direction for deliveringfibers to said spinning nip and by said moving guide surface; saidmoving guide surface moving in said direction for delivering fibers tosaid spinning notch at a speed substantially equal to the surface speedof said casing surface.
 11. An open-end spinning device for spinningfibers, comprising two friction rollers driven in the same direction andforming a yarn forming zone and a spinning nip therebetween forreceiving fibers, wherein at least one of said two friction rollers isprovided with a first sector subjected to suction in said spinning nip,in the range of said yarn forming zone, the width of said first sectorextending, in the peripheral sense, from said yarn forming zone throughsaid spinning nip to beyond a plane connecting the axes of said twofriction rollers, and wherein the middle of said first sector is locatedat a distance from said plane connecting the axes of said two frictionrollers, in the peripheral sense, on the side of said plane opposite tosaid spinning nip.
 12. An open-end spinning device as defined in claim1, wherein the width of said first sector is between 4 and 8 mm.
 13. Anopen-end spinning device as defined in claim 1, wherein the width ofsaid first sector is 6 mm.
 14. A open-end spinning device as defined inclaim 1, wherein one of said two friction rollers rotates toward thespinning nip in the direction which the spinning nip receives fibers,said one of said two friction rollers being provided with said firstsector.
 15. An open-end spinning device as defined in claim 14, whereina second sector of lesser suction than said first sector is providedsaid one of said two friction rollers, preceding said first sector, forconveying fibers into said yarn forming zone.